Current references may be designed to provide a source of substantially constant current, typically used in turn by other circuits which depend upon a minimal variance in the supply of current. In fact, the ultimate performance of a circuit which makes use of a current reference is often dependent on the stability of the reference.
One problem with current reference circuits may be that the current provided is sensitive to voltage, temperature, and process variations. Thus, as supply or bias voltage, temperature, or process parameters (such as transistor threshold voltages) vary, the current generated by the reference may also vary. Thus, sensitivity to temperature and power supply voltage variations in current references, and the reduction thereof, has been the subject of much study. See, for example, Sueng-Hoon Lee and Yong Jee, “A Temperature and Supply Voltage Insensitive CMOS Current Reference,” IEICE Trans. Electron., Vol. E82-C, No.8, August 1999; and Cheol-Hee et al., “A Temperature and Supply Insensitive CMOS Current Reference Using a Square Root Circuit,” IEEE ICVC, Oct. 1997, pp 498-500.